In the past, magnetoresistors were believed to be best formed from high carrier mobility semiconductive material in order to get the highest magnetic sensitivity. Hence, the focus was on making magnetoresistors from bulk materials that were thinned down or on films having sufficient thickness to exhibit a high average mobility.
We have found a new way to approach making magnetoresistors. We have found that if an accumulation layer is induced in the surface of an extremely thin film of semiconductive material, the properties of the accumulation layer relevant to magnetic sensitivity can dominate over those of the remainder of the film.
Such accumulation layers can make higher band gap semiconductor materials useful in magnetosensors. Such materials can be used at higher operating temperatures than lower band gap semiconductive material, such as indium antimonide. However, it may even enhance the sensitivity of indium antimonide enough to allow it to be used at higher temperatures.